Wilhelm schmidt



PATENTED JAN. 26, 1904.

W. SCHMIDT. PISTON VALVE FOR STEAM ENGINES.

APPLICATION FILED SEPT. 27, 1901.

N0 MODEL.

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fatentd .Iamiary 26, 1904.

PATENT OFFICE.

WILHELM SCHMIDT, OF WILHELMSHOHE, NEAR CASSEL, GERMANY.

PISTON-VALVE FOR STEAM-ENGINES;

SPECIFICATION forming part of Letters Patent No. 750,400, dated January26, 1904.

Application filed September 27, 1901. Serial No. 76,770. (No model.)

To all whom it may concern:

Be it known that I, WILHELM SCHMIDT, a subject of the King of Prussia,German Emperor, and a resident of Wilhelmshohe, near Cassel, in theProvince of Hesse-Nassau, German Empire, haveinvented certain new anduseful Improvements in Piston Valves for Steam-Engines, of which thefollowing is an exact specification.

My invention relates to improvements in piston-valves for steam-engines,and has especially for its purpose to provide a solid pistonvalvewithout any piston-rings, in which piston-valve means are provided toavoid awearing out of the valve-piston and of the valvechest.

My invention is represented in the accompanying drawings, in whichFigure 1 is a longitudinal section of the valvechest provided with mynew arrangement. Fig. 2 is a cross-section on lineA B of Fig. 1.

' Fig. 3 is a longitudinal and a cross section of a modifiedconstruction of the valve-piston. Fig. 1 is a section on line C D ofFig. 1.

It is known that piston-valves with solid pistons without anypiston-rings have the great advantage of a simple construction in whichthe wearing out of the valves is nearly perfectly avoided. Up to date itwas not possible to use such solid valve-pistons for large engines, asin case the valve-pistons were fitted in tight enough to avoid greatlosses of steam a fraying and chocking of the pistons easily took placeon account of differences in the heating of the piston and thevalve-chest and the different expansion hereby effected. In order toavoid this disadvantage, I provide means for equally heating thevalve-piston and the valve-chest and herewith efiecting always an equalexpansion of these parts.

The piston-valves are constructed for double admission after the mannerof the so-called trick-valves. Contrary to the constructions known up todate the admission takes place from the middle of the-yalve-chestsbetween the two valve-pistons. This arrangement has the advantage thatin case of superheated steam being used the stufiing-boxes work only inthe exhaust-steam, and only a very small part of the valve-chest comesin contact with the superheated steam. The valve-pistons a are situatedin removable bushings b, in which an annular channel Z) is provided.This channel b can either be cast in, as shown on the right-hand sideofFig. 1, or a groove can be turned in, which groove is closed by thevalvechest cover 0, as shown on the left-hand side of Fig. 1. Theannular channels 6 are connected with the admission-room by means ofchannels .9, situated on the outside of the bushings, so that in casethe steam enters the valvechest this steam immediately enters thechannels s and the annular channels I), hereby effecting an equalheating of the whole bushings b.

In order to attain a still better effect, the valve-pistons can beconstructed so as to avoid too rapid a heating of the same. In order toattain this, an isolating-cover a may be provided at the inside of thevalve-piston, leaving an annular channel a between this cover and thepiston proper, as shown on the righthand side of Fig. 1.

In Fig. 3 another construction of the valvepiston a is shown. In thisconstruction the annular channel a, situated at the side toward theentrance of the steam, is connected, by means of channels t, with theother side of the piston -that is to say, with the side at which theexhaust-steam leaves the valve-chest. It is hereby attained that theexhaust-steam enters the channel a through the channels tand herewitheffects a cooling of the valve-piston.

In case of large valve-chests a still better and more equal heating ofthe bushings b can be attained by providing a second annular channel 6around these bushings.

In case of highly-superheated steam being used it will be advantageousto provide at the same time means for heating the bushings b andpreventing too rapid a heating of the pistons a or effecting a coolingof the same.

Having thus fully described the nature of this invention, what I desireto secure by Letters Patent of the United States is- 1. In piston-valvesfor steam-engines, the combination with a valve-piston, of a removablebushing forming the valve-seat, annular channels provided in saidbushing, and channels connecting said annular channels to the heatingthe bushings by the admission-steam and the piston by the exhaust-steam,substantially as described and for the purpose set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing Witnesses.

WILHELM SCHMIDT.

Witnesses:

WOLDEMAR HAUPT, HENRY HASPER.

